/Engine/Plugins/Experimental/GeometryScripting/Source/GeometryScriptingCore/Public/GeometryScript/PolygonFunctions.h
Returns a vertex's tangent of a Simple Polygon. VertexIndex loops around, so e.g., -1 gives the tangent of the last vertex in the polygon. If Polygon has no vertices, returns the zero vector.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="GeometryScript|SimplePolygon", Meta=(ScriptMethod)) static FVector2D GetPolygonTangent ( [FGeometryScriptSimplePolygon](API\Plugins\GeometryScriptingCore\GeometryScript\FGeometryScriptSimplePolygon) Polygon, int32 VertexIndex, bool & bPolygonIsEmpty )